1. Technical Field
This invention relates generally to procedures and equipment for stopping an existing line containing fluid under pressure, and more particularly to a valve insertion method and associated ball valve assembly for inserting a valve in a line without having to shut down the line during the insertion.
2. Description of Related Art
An existing ball valve includes a spherically shaped valve element or ball within a valve housing that has a first or input port facing in a first direction and a second or output port facing in an opposite second direction. The housing defines a passageway for fluid flow. The passageway extends between the first and second ports along a central axis of the passageway. The ball occupies a position in the passageway that is intermediate the two ports so that the central axis of the passageway passes through the ball.
The ball is mounted within the housing movably so that an operator can twist a valve handle and thereby rotate the ball about an axis of ball rotation that is perpendicular to the central axis of the passageway. The operator can rotate the ball ninety degrees between a first (or open) position of the ball and a second (or closed) position of the ball. In the open position, a bore extending through the ball aligns with the central axis of the passageway so that fluid can flow through the bore. In the closed position, the bore is disposed transversely to the central axis of the passageway so that the ball blocks fluid flow.
The existing ball valve is installed in a line by coupling an input leg of the line to the input port and an output leg of the line to the output port. To insert the ball valve in an existing line containing fluid under pressure, the installer must first shut down the existing line so that it is no longer pressurized. Next, he cuts the line and then he installs the ball valve. Doing so disrupts service, and it can be quite time consuming and expensive. Thus, installers need a better way to insert a ball valve in an existing line containing fluid under pressure without having to shut down the line.